1. Field of the Invention
The present invention relates to a drawing apparatus, and a drawing-data-generation apparatus therefor, in which drawing data, which is required to perform a drawing operation on drawing blocks on a surface that can be drawn at one time by drawing heads moving relatively to the drawn surface, is sequentially generated based on design data and temporarily stored in a memory and, then, sequentially supplied to drawing engines, as well as a drawing method and a drawing-data-generation method therefor, in which drawing data, which is required to perform a drawing operation on drawing blocks on a surface that can be drawn at one time by drawing heads of a drawing apparatus moving relatively to said drawn surface, is sequentially generated based on design data and temporarily stored in a memory and, then, sequentially supplied to drawing engines of said drawing apparatus.
2. Description of the Related Art
Generally speaking, wiring patterns of circuit boards are formed by exposing and developing substrates, based on design data on the wiring patterns to print the desired patterns on the substrates and, then, etching the substrates. In this exposure process, photomasks are typically used.
However, in the exposure process using the photomasks, as a substrate on a stage and a photomask are aligned with each other mechanically by moving them relatively, accuracy is degraded. Further, as the exposure process is affected profoundly by physical and chemical parameters, the substrate in exact accordance with drawing data cannot always be obtained after the exposure. For example, as the substrate itself may expand, shrink or distort due to ambient temperature of the substrate, mechanical stress applied to the substrate and the like, it is necessary to empirically optimize different process conditions (i.e. to empirically make adjustments of different process conditions) so that the desired pattern can be obtained by remaking photomasks of different layouts several times in consideration of such expansion, shrinkage or distortion. Still further, before mass production, in order to obtain optimal values for exposure conditions such as the dose of exposure, the exposure speed, the focus of light sources and so on, a set of inspections called “optimization” must be performed repeatedly to determine the optimal exposure conditions. In the exposure process using the photomasks, as the photomasks are needed even at the experimental stage where inspections are repeated many times, not to mention in the mass production of substrates, it is costly and very uneconomical to manufacture the masks.
In order to address the problem described above, in recent years, various patterning methods by direct drawing without using the photomasks have been proposed. According to the patterning methods by the direct drawing, the expansion, shrinkage, distortion or displacement of the substrate described above can be corrected either in advance in the stage of generating the drawing data or in real time and, therefore, improvements can be made such as increase in manufacturing accuracy, increase in yield, shortening of delivery times, reduction of manufacturing cost and so on.
Examples of the patterning methods by the direct drawing include: a method of forming exposure patterns by a direct exposure process using Digital Micromirror Device (DMD) or an electron beam exposure machine; a method of directly forming wiring patterns using an inkjet patterning machine having ink discharge heads; a method of directly forming resist patterns for etching process; and so on. Among these methods, in a typical conventional example of the patterning method by the direct exposure using DMD set forth in Japanese Unexamined Patent Publication No. 10-112579, when a resist formed on a substrate is exposed, pattern data is generated according to a pattern to be exposed, then, this pattern data is input to a Digital Micromirror Device (DMD), a plurality of micromirrors of the DMD are tilted according to the pattern data and, then, light is projected on the DMD so that the resist is illuminated by the light reflected from the micro mirrors and exposed in a shape according to the pattern data.
FIG. 9 is a diagram schematically showing a direct drawing system.
A direct drawing system 100 comprises: a drawing apparatus 101; and a computer 102 connected to the drawing apparatus 101. The computer 102 supplies drawing data to the drawing apparatus 101 and controls the drawing apparatus 101. The drawing apparatus 101 comprises: a stage 110 on which a substrate 151 is mounted; and drawing means 111 that moves above the drawn substrate 151 relatively thereto in the direction of the arrow in the figure. The drawing means 111 comprises a plurality of drawing heads (or drawing engines) (not shown), each of which is assigned to respective areas to be drawn on a surface of the substrate 151 and each of which performs drawing operations in parallel. Here, in the drawing means 111, the drawing heads are exposure heads in the case of the maskless exposure machine or the drawing heads are ink discharge heads in the case of the inkjet patterning machine.
FIG. 10 is a diagram showing an operating principle of the direct drawing apparatus, and FIG. 11 is a flow chart showing a data process flow of the direct drawing apparatus.
The drawing means 111, which moves above the substrate 151 relatively thereto, comprises a plurality of drawing heads #1-#N (reference numeral 30) (where N is a natural number) aligned in the direction orthogonal to the relative movement of the substrate 151.
The substrate 151 is spatially divided into N areas referred to as “strips #1-#N” (reference numeral 32). Each drawing head #1-#N (reference numeral 30) performs drawing on the respective strips #1-#N (reference numeral 32) while moving relatively to the substrate 151 at a speed of Vex. Here, the length of the substrate 151 in the direction of the relative movement or, in other words, the length of the strips #1-#N (reference numeral 32) is defined as L (hereinafter referred to as the “strip length”).
The area that can be drawn at one time by each drawing head #1-#N (reference numeral 30) is limited and, in the direction of the relative movement of the substrate 151, it has a length shorter than the strip length L. Therefore, each strip #1-#N (reference numeral 32) is spatially divided into respective M (where M is a natural number) “drawing blocks (i, j) (where 1≦i≦N, 1≦j≦M, the drawing blocks may be hereinafter simply referred to as “blocks”)” (reference numeral 33) and the drawing operation is performed for each block (i, j) in a block-by-block manner. Here, the length of the block (i, j) in the direction of the relative movement is defined as ΔY. Therefore, a relationship of L=M×ΔY holds between the strip length L and the length ΔY of the block (i, j) in the direction of the relative movement. Here, the length of each block (i, j) in the direction orthogonal to the relative movement of the substrate 151 is equal to the width of each strip #1-#N (reference numeral 32).
The drawing data is typically bitmap data. The bitmap data has a very large data volume and, therefore, it is not preferable that a large amount of memory resources is required to generate and store the bitmap data in advance before performing the drawing operation. Therefore, in order to save the memory resources, the drawing data in bitmap form is generated based on design data so that it is spatially divided and assigned to each drawing head #1-#N (reference numeral 30) in real time during the drawing operation and it is temporarily stored in the memory and, then, sequentially supplied to the respective drawing heads #1-#N (reference numeral 30). The drawing heads #1-#N (reference numeral 30) performs the drawing operation based on the supplied drawing data in bitmap form.
As shown in FIG. 11, first, design data 51 is converted into intermediate data through a first data conversion process S101. Thus, the intermediate data 52 is formed by processing the design data 51 consisting of CAD data so that bitmap data can be more readily generated therefrom. Here, the intermediate data 52 has a smaller data volume than that of the bitmap data described below and, therefore, it may not be necessary to perform the first data conversion process S101 in real time during the drawing operation and the intermediate data 52 may be generated in advance and stored in the memory.
In step S102, the intermediate data for one drawing block is read. Then, with regard to the intermediate data read for the one drawing block, an alignment and correction process S103 is performed and, then, in step S104, the bitmap data 53 is generated and temporarily stored in the memory. In step S105, the bitmap data 53 is supplied to the respective drawing heads. Here, the real time processes S102-S105 described above are collectively referred to as a “second data conversion process”. Each drawing head performs the drawing operation using the bitmap data 53 for each drawing block supplied through the second data conversion process. After the drawing operation of each drawing head for the respective one drawing block is completed, the process returns to step S102, where the second data conversion process is performed to obtain the bitmap data 53 for the next drawing block.
As described above, the drawing data used in the drawing process has a very large data volume, such as in the bitmap data form. Therefore, in order to save the memory resources, the drawing data is generated based on the design data in a block-by-block manner in real time during the drawing operation and the drawing data is supplied to the respective drawing heads. In other words, the drawing data for each drawing block is “produced” in real time by the second data conversion process described above and, then, sequentially “consumed” at a constant speed in a block-by-block manner in the respective drawing heads.
At this time, if the amount of “consumption” described above is larger than the amount of “production”, losses of the drawing data to be supplied to the drawing heads occur and, therefore, the drawing process cannot be performed accurately. Such a problem is likely to occur, for example, when the alignment and correction process in FIG. 11 is complicated or the content of the drawing data for a particular drawing block is especially complicated.
In order to address this problem, it may be contemplated to temporarily inhibit or suspend the “consumption” when the “consumption” is likely to be excessive. More specifically, to inhibit or suspend the “consumption” is equivalent to changing the moving speed Vex of the substrate 151 relative to the drawing engines. However, for example, in the case when the drawing apparatus is a maskless exposure machine, wherein, as the relative moving speed Vex is reduced, a dose of exposure, or a cumulative light energy value applied to a certain area, is increased, optical energy of an exposure light source also must be controlled to obtain a constant dose of exposure and, therefore, the control of the entire system to obtain stable exposure results will become very complicated, which will result in increased manufacturing cost. Moreover, to reduce the relative moving speed Vex is equivalent to reducing the exposure speed, which will result in degraded productivity.
Alternatively, it may also be contemplated to generate all drawing data based on the design data before performing the drawing operation and store it in the memory so that the amount of “consumption” described above is never larger than the amount of “production”. However, because the drawing data has a very large data volume as described above, a large amount of memory resources is required to store the data, which will also result in increased manufacturing cost.
Therefore, in view of the above problems, it is an object of the present invention to provide a drawing apparatus and a drawing-data-generation apparatus for the drawing apparatus as well as a drawing method and a drawing-data-generation method for the drawing method that can efficiently perform stable drawing operations in the case when drawing data required for the drawing operations is sequentially generated based on design data and sequentially supplied to drawing engines.